Flexural Properties of Sandwich Panels with Perforated Core - Hole Number and Pattern Investigation

Composite sandwiches are effective structures that have high stiffness to weight ratios. In this paper the feasibility of manufacturing sandwich panels by vacuum assisted resin transfer molding without the distribution media has been investigated experimentally. Composite sandwich panels were made by using E-glass fiber/ Polyester resin facing and a rigid PVC foam core. To improve surface quality and feasibility production sandwich panel by VARTM the core was perforated. Holes had square repeat pattern with 2 mm diameters. Three point bending and Cracked Sandwich Beam (CSB) tests were used to investigate the effect of perforated cores. Also the effect of different hole patterns on mold filling time and final part weight were investigated. The perforation of core increases the maximum bending load and absorbed fail energy up to 29 and 90%, respectively. Perforated core increases the permeability and result to increase flow front speed and decreases the mold filling time up to 20%. But these holes which were filled by resin, slightly increase the sandwich final weight. The maximum increase in weight was 1.4%. Perforated cores increase slightly the debonding interface strength between face and core but, crack may be temporarily arrested when it meets a resin filled hole but this localized arrest is minor.

Keywords:

Sandwich Panel , Hole Pattern , Mechanical Properties , Three Point Bending , VARTM